1. Technical Field
The present disclosure relates to a control device for a vehicle lamp, the vehicle lamp, and a method of controlling the vehicle lamp.
2. Related Art
An automatic leveling control, which changes an irradiation direction by automatically adjusting the position of an optical axis of a vehicle headlight according to an inclination angle of a vehicle, has been known in the past. In automatic leveling control, a vehicle height sensor is used as an inclination detector of a vehicle and the position of an optical axis of a headlight is adjusted based on a pitch angle of a vehicle that is detected by the vehicle height sensor. Meanwhile, a structure, which performs automatic leveling control using a gravity sensor as an inclination detector, is disclosed in JP-A-2000-085459. Further, a structure, which performs automatic leveling control using a three-dimensional gyro-sensor as an inclination detector, is disclosed in JP-A-2004-314856.
If an acceleration sensor, such as a gravity sensor or a three-dimensional gyro-sensor, is used as an inclination detector of a vehicle, it may be possible to reduce the manufacturing cost and weight of an automatic leveling system as compared to a case where a vehicle height sensor is used. Meanwhile, the inventors have recognized that there is the following problem in the automatic leveling control using the acceleration sensor in the related art.
That is, an inclination angle detected by the acceleration sensor is an inclination angle of a vehicle with respect to a horizontal plane that includes an inclination angle of a road surface with respect to the horizontal plane and an inclination angle of a vehicle with respect to the road surface. Meanwhile, an inclination angle of a vehicle required for the automatic leveling control is an inclination angle of a vehicle with respect to the road surface. Meanwhile, when a detected value of the acceleration sensor is changed in the automatic leveling control in the related art, the position of an optical axis has been adjusted without determining whether the change of the detected value of the acceleration sensor is the change of the inclination angle of a road surface with respect to a horizontal plane or the change of the inclination angle of a vehicle with respect to the road surface. For this reason, it has been desired to accurately adjust the position of an optical axis in the automatic leveling control using the acceleration sensor in the related art.